Strip for use in stabilized earth structures and method of making same

ABSTRACT

A strip for use in a stabilized earth structure has a tensile portion in the form of an elongate core which supports lateral friction wings and optional ribs. The elongate core may be steel or a polymer material and the wings are fabricated from a plastic material. Alternatively, the strip may be made from a single material (e.g., plastic) with a thickened region defining the core and thinner regions providing the friction wings.

CROSS REFERENCES TO RELATED APPLICATIONS

This application corresponds to PCT International Application No.PCT/GB94/02286 filed Oct. 19, 1994 and priority applications filed inthe United Kingdom as Application No. 9321792.5 filed Oct. 22, 1993 andApplication No. 9417134.5 filed Aug. 23, 1994 upon which a claim forpriority is made.

CROSS REFERENCES TO RELATED APPLICATIONS

This application corresponds to PCT International Application No.PCT/GB94/02286 filed Oct. 19, 1994 and priority applications filed inthe United Kingdom as Application No. 9321792.5 filed Oct. 22, 1993 andApplication No. 9417134.5 filed Aug. 23, 1994 upon which a claim forpriority is made.

BACKGROUND OF THE INVENTION

This invention relates to a stabilising strip for use in stabilisedearth structures.

A stabilised earth structure is one in which stabilising elements, suchas elongate strips, are combined with backfill, such as earth, in orderto form a composite material. The strips extend rearwardly from a facinginto the backfill and are horizontally and vertically spaced from eachother. Such structures are commonly employed to provide retaining wallsand abutments for bridges. They are known from, for example, GB-A-1 069361 incorporated herewith by reference.

In the vast majority of cases, the stabilising elements are provided inthe form of strips having a length of between about 3 and 10 m, althoughshorter strips and occasionally longer ones of up to about 20 m may beused. The width of the strips is generally between 4 and 6 cm althoughit is known to use strips of up to 10 or 25 cm in width. Their thicknessranges from about 1 mm to a few centimeters and is generally in therange of 1 to 6 mm.

The purpose of the stabilising strips is to transmit forces within theearth mass and to distribute stresses. In particular, it is firstlynecessary to transmit forces between a strip and the backfill in whichit is placed and therefore the strip must have a sufficiently largesurface area to develop through friction the required shear resistanceper unit length. In order to increase the shear resistance, the width ofthe strip must be increased. The surfaces of the strip may also beprovided with laterally extending ribs to increase the frictionalinteraction with the earth, as is known from GB-A-1 563 317 incorporatedherewith by reference.

Secondly, the strips must be capable of transmitting forces along theirlength and therefore it is necessary that they have a high tensilestrength.

As well as these two main functions which are fundamental to the basicoperation of the stabilised earth structure, various othercharacteristics are also highly desirable. A reinforcing strip should beable to flex in a vertical plane in order to accommodate soildeformation, such as settlement or shrinkage, without being damaged; thestrip should have a high breaking strain, to give good elongation beforeit breaks; and the strip should also be durable, having a slow andpredictable rate of degradation with time, even in an aggressivebackfill environment. When steel strips are used, these requirementsgenerally make it necessary to use strips of at least 4 or 5 mm inthickness in order to provide the necessary strength, bearing in mindthe effects of degradation over time. When this thickness is combinedwith the width of the strip which is required in order to providesufficient frictional interaction with the earth, the result is atechnical over-design in terms of the tensile capacity of the strip,particularly for low structures and the upper part of higher structures.It will be appreciated therefore that strips having a high weight perunit length are employed, such that the strips are heavy to transportand install, as well as expensive.

SUMMARY OF THE INVENTION

The invention provides a strip for use in stabilised earth structures,comprising a longitudinally extending tensile portion for resistingtensile force, and a lateral portion which projects laterally of thetensile portion for frictional engagement with earth.

Thus, the tensile portion can be designed or selected in accordance withthe required tensile resistance of the strip, whilst the lateral portioncan be separately designed or selected in accordance with the requiredfrictional engagement forces to be mobilised. Therefore the strip may bedesigned to optimise its performance in both of these respects whilstproviding a more economical use of the material or materials from whichthe strip is made.

It will be appreciated that the tensile portion will generally extendacross only part of the width of the strip, for example less than halfor less than one third. Preferably the tensile portion extends acrossabout one quarter of the width of the strip, and possibly one tenth. Thelateral portion will then project laterally across the remaining part ofthe width. Thus, in general, the extent of lateral projection of thelateral portion will be substantially greater than the thickness of thestrip.

In practice, the surfaces of the strip immediately above and below thetensile portion will be in contact with the earth above and below andwill thus make a greater or lesser contribution to the frictionalengagement with the earth, depending on the size and profile of thesesurfaces. This will be in addition to the frictional capacity of thelateral portion. Moreover, the lateral portion may make a contributionto the tensile resistance of the strip.

However, as the function of transmitting the stresses within thestructure along the length of the strip is primarily carried out by thetensile portion of the strip, only this portion need be strong enough tocarry the tensile loads. Therefore, there is no need for the lateralportion to have a high tensile strength and so in order to savematerials it is preferred that the tensile portion has a higher totaltensile strength than the lateral portion.

In a typical example, a 6 m length strip may be subject to a maximumtensile load of 15 to 20 kN. Assuming a maximum tensile force of 16 kNand a cross-sectional area of the tensile portion of 80 mm², there willbe a tensile stress of 200MN/m². The maximum shear stress resulting fromthe transmission of frictional forces from the lateral portion to thetensile portion may typically be about 1MN/m². Hence, although the twostresses are not directly comparable since one is a tensile stress andthe other one a shear stress, the stress which will have to be sustainedby the tensile portion is about two orders of magnitude larger than thestress that will have to be sustained by the lateral portion.

This explains why considerable savings may be obtained by separating thetwo functions of tensional and frictional capacity, for example by usingtwo different materials, or two different thicknesses, or a combinationof both, or the same materials and thicknesses and with the lateralportion including perforations.

The tensile portion and the lateral portion may thus be of the samethickness, if the tensile portion is made from a stronger material thanthe lateral portion, or if the portions are of the same material but thelateral portion includes perforations.

Preferably, however, the tensile portion is thicker than the lateralportion. The minimum thickness to provide the necessary tensile strengthis only required in the tensile portion and therefore the lateralportion may be made much thinner because the stresses acting upon it arecomparatively low. In fact, even if a localised area, for example a fewsquare centimeters, of the lateral portion were to disappear throughdegradation, this would not significantly impair the stability of thestructure. Thus the cross-sectional shape of the lateral portion is intheory ideally a wide and thin section, but for practical purposes maybe other shapes where the ratio of its perimeter/cross-sectional area islarge. Preferred shapes are a thin rectangle or two or more thinrectangles.

A thicker tensile portion is generally preferred, in order to provide alow ratio of its perimeter/cross-sectional area. This decreases thecontact with the environment for any given cross-sectional area of thetensile portion. Consequently the section of the tensile portion is intheory ideally circular, but for practical purposes may be circular,oval, square, rectangular or other shapes where theperimeter/cross-sectional area ratio is small.

The preferred requirement that the tensile portion is thicker than thelateral portion will generally apply along the full length of the strip.However, it may be appropriate in certain circumstances to provideregions where the tensile portion is thinner than it is in the remainderof the strip, for example, at the end of the strip furthest from thefacing where the tensile forces are lowest.

If different materials are used for the lateral portion and the tensileportion, they may have substantially different properties. For examplethe tensile portion could be formed of a strong material such as steelor polymer yarns or drawn bulk polymer and the lateral portion may bemade of a material which may not be mechanically very resistant but isresistant to degradation such as some plastics materials likepolyethylene or polypropylene. The use of plastics to provide thelateral portion is also advantageous because these materials arelightweight and easy to form with appropriate surface texture,perforations etc.

The tensile and lateral portions of the strip may be provided indifferent ways depending upon the profile chosen for the strip and thechoice of materials. For example, the lateral portion may projectlaterally on one side only of the strip. Preferably however the tensileportion is a core from which lateral portions project laterally on bothsides. Thus, the lateral portions may be in the form of friction wingsextending on opposite sides of the core.

Alternatively, the tensile portion may comprise a plurality of coresinterconnected by the lateral portion. For example, two cores may beprovided. Thus, the tensile loading could be divided between the twocores and these cores may be connected together by the lateral portion,which may also have wings at the sides of the strip.

It is possible that the strip could be formed with a smooth outersurface and the frictional interengagement with the earth could then beprovided simply by having a sufficiently large surface area for thelateral portion. However, it is preferred that the lateral portion beprovided with a surface which has been adapted to resist longitudinalmotion through the earth. Therefore, preferably, the lateral portion isprovided with ribs and/or corrugations and/or perforations to improvethe frictional interaction with the earth. Corrugations, ribs or a roughsurface may be obtained by pressing the strip into hot or cold dies, orby gluing, pasting or welding to the strip a corrugated/ribbed/roughcoating. The various means for improving frictional interaction may ifdesired be provided across the surfaces of the strip above and below thetensile portion, and not just on the lateral portion.

In general, the lateral portion will extend longitudinally of the strip,preferably continuously but if short breaks are provided at longitudinalintervals this may not significantly affect its performance. Any suchbreaks will normally be shorter than the remaining lengths of thelateral portion.

The tensile portion of the strip may typically have a cross-sectionalarea in the range from about 15-400 mm², for example about 100 mm². Atensile portion of circular cross-section may have a diameter of about5-16 mm and more usually about 8-12 mm, whilst a tensile portion ofrectangular cross-section may have a width of about 15-30 mm and athickness of about 4-15 mm but more usually about 5-8 mm. The totalstrip width may be about 20-80 mm and more usually about 40-70 mm. Thethickness of the lateral portion may be about 1-5 mm or 1-3 mm, plus 1-3mm ribs if these are provided. The ratio of the tensile portionthickness/lateral portion thickness may typically be in the range 2-4.The above figures are merely examples and other dimensions may bedesired or required in certain circumstances, for example with veryshort or very long strips. The figures given are also particularlyapplicable to substantially all steel strips or strips with a steeltension portion and a plastics lateral portion, although in practicethey may also apply to other forms of strip, such as polymer/plasticsstrips.

The strips may be designed to be impermeable to water. However, in somecircumstances it may be useful to provide a strip which permits entry ofwater thereto and longitudinal transport of water therealong. Becausewater can flow into such a strip and then along it, the strip may beused to drain the backfill within which it is located, reducing the porewater pressure. For example, water may be transported to the front of anearth structure and allowed to drain away. By removing water, theadherence between the strip and the backfill material is increased andso, for a given number or surface area of stabilising members, a lowerquality, less well draining backfill material may be used. Thus, thesestrips may be employed in areas where the available backfill materialis, for example, clay, without the need to incur the expense oftransporting better quality backfill material from elsewhere. Thedrainage property of the strip also speeds up consolidation of thebackfill.

The transport of water from the inside of a structure to the surface isalso advantageous when the facing includes vegetation growth andconditions are dry, since water can be transferred to the vegetation.

Various methods may be used to secure the strip to the facing of astabilised earth structure. The strip may have at one end an integralpad adapted to have formed therethrough an aperture suitable to receivefastening means, such as a vertical pin or bolt, to locate the strip ina stabilised earth structure, the thickness of the pad being greaterthan the thickness of the lateral portion. The pad may be thicker thanthe tensile portion or it may be more convenient for it to have the samethickness. In one example, the cross-sectional shape of the pad isrectangular, whereby the pad has a uniform thickness across its width.In another example, when viewed in cross-section, the pad has a thickcentral region and a thinner lateral region on each side thereof, boththe central and the lateral regions being thicker than the lateralportion elsewhere in the strip. Typically, the pad is 40-100 mm inlength. The pad may be formed by various means such as by hot forging,but preferably the strip is rolled to include thickened pads atlongitudinal intervals, as is known from GB-A-2 177 140. The strip isthen cut so that one of the pads is located at an end of the strip andcan be formed with a vertical hole for receiving a pin for connection tothe facing. In the case of the composite strips, the pad will normallybe formed integrally with the tensile portion thereof.

In a stabilised earth structure the facing is designed to take the localloads exerted by the adjacent backfill. If the strips are widely spacedfrom each other, a stronger facing is required to resist backfillpressure; in other words, the required strength of the facing isdirectly dependent on the strip spacing. As discussed above in relationto known strips, there is a lower limit to the strip thickness to allowfor degradation and there is a lower limit to the strip width to ensureadequate frictional interaction with the earth, with the result of apractical lower limit to the strength of the strip. In existingstructures this has led, for reasons for economy, to a relatively smallnumber of strong strips at wide spacings and to the requirement for arather strong facing. Another advantage of the strip of the presentinvention is that the minimum strength of the strip can be decreasedleading to a less strong and less expensive facing.

The present invention also extends to a stabilised earth structurecomprising stabilising strips as set out herein. Such a structure canbenefit both from economical strips and an economical facing.

There are two main classes of manufacturing methods by which stripsaccording to the invention may be made. First, the strip may be madefrom a single type of material. Second, a plurality of materials may becombined.

In the first case, separate pieces of the same material may be glued,welded, or joined together by other means. Preferably, however, thestrip is made from a single piece of material formed into an appropriateshape, for example by casting. A preferred method of making astabilising strip comprises rolling a blank to form the strip.

The strip may be rolled in a single stage, or, alternatively, a firstrolling stage may provide the general outline and then a further stagemay add ribs, corrugations or perforations as appropriate. Thus, forexample, the method may further comprise the step of cutting aperturesin the lateral portion.

In the second case, the lateral portion could be attached to the tensileportion in a number of ways, such as by welding or by the use of clamps,bolts, adhesives, etc. However, it is particularly preferred that thetensile portion be surrounded by the material which forms the lateralportion. By encasing the tensile portion in this way it may be protectedfrom corrosion by the material which also forms the lateral portion, aswell as providing a strong connection between the portions.

In order to improve adherence between the lateral portion and thetensile portion, the tensile portion may be provided with ribs or thelike.

The material forming the lateral portion may be moulded around thetensile portion or, alternatively, it may be provided in two separateparts which are brought together with the tensile portion sandwichedtherebetween. The parts may be glued, hot welded (e.g. by a pair ofpress and weld cylinders), hypersonically or ultrasonically welded orattached by other appropriate means.

BRIEF DESCRIPTION OF THE DRAWINGS

Certain preferred embodiments of the invention will now be described, byway of example only, with reference to the accompanying schematicdrawings:

FIG. 1 is a perspective view of a first embodiment of the invention;

FIG. 2 is a perspective view of a second embodiment of the invention;

FIG. 3 is a perspective view of a third embodiment of the invention;

FIG. 4 is a perspective view of a fourth embodiment of the invention;

FIG. 5 is a perspective view of a fifth embodiment of the invention;

FIG. 6 is a perspective view of a sixth embodiment of the invention;

FIG. 7 is a perspective view of an apparatus for producing stripsaccording to the invention, wherein material forming the lateral portionis moulded around the tensile portion;

FIG. 8 is a perspective view of an alternative apparatus for producingstrips according to the invention wherein the material forming thelateral portion is moulded around the tensile portion;

FIG. 9 is a perspective view of an apparatus for producing stripsaccording to the invention wherein the tensile portion is sandwichedbetween the parts forming the lateral portion;

FIG. 10 is an apparatus for producing strips according to the inventionusing a pair of rollers;

FIG. 11 is an apparatus for producing strips according to the inventionusing rollers and incorporating a perforating stage;

FIG. 12 is a perspective view of a seventh embodiment of the invention;and

FIG. 13 is a schematic view of one end of the strip of FIG. 12.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Turning first to FIG. 1 there is illustrated a strip 1 for use in astabilised earth structure which has a tensile portion in the form of asteel core 2. This is surrounded by a casing 3 which has a pair oflaterally projecting portions in the form of friction wings 4. At thetip of each wing 4 a thickened bead 6 is provided. In order to assist inthe engagement of the friction wings with soil, the wings are providedwith small vertically projecting ribs 5, provided alternately on the topand bottom faces of the strip (the bottom ribs not being shown).

The core 2 may be made out of a steel bar which may have a smoothsurface, or be sanded, gritted or otherwise roughened or deformed toenhance adherence to the friction wings. Thus a deformed or highadherence reinforcing bar of the type normally used to reinforceconcrete may be used, or a smooth reinforcing bar may be used. The coremay alternatively be made of other materials such as stainless steel oraluminium alloys.

The casing 3 may be made of a polymer material such as polyethylene,polypropylene, PVC etc. This may be treated to resist UV light by theaddition of carbon black and its strength may be increased by theaddition of glass fibre. Other additives such as talc may be used toenhance durability or resistance to impact.

The diameter of the core 2 may be anything from a few millimeters to afew centimeters but is usually in the range 5-15 mm. In the example ofFIG. 1, the diameter is 10 mm. The thickness of the friction wings 4 is3 mm, the diameter of the beads 6 is 5 mm, and the height of the ribs 5is 2 mm.

A similar structure may be employed when a core of polymer is used. Sucha strip 1 is illustrated in FIG. 2. In this figure the core 2 issomewhat flatter in profile than that of FIG. 1 and therefore the casing3 is shaped accordingly. It will be noted that in this embodiment theribs 5 extend most of the way across the width of the strip 3 andtherefore extend above and below the core 2 as well as on the frictionwings 4. The core 2 may consist of a tension resistant polymer in itsbulk form, in drawn members, or in jointed yarns.

FIG. 3 illustrates a third type of strip 1, in which two steel cores 2are provided, each formed from a reinforcing bar. These are laterallyspaced and interconnected by the casing 3 which has two small frictionwings 4 on opposite lateral sides of the strip and a larger centralinterconnecting part 26 between the two cores. Ribs 5 are provided onall three parts of the casing 3 although because of its larger size,larger ribs are formed on the central part 26.

FIGS. 4 to 6 illustrate embodiments of the invention which are made froma single type of material. FIG. 4 illustrates a strip 1 which is thefourth embodiment of the invention. This has a thick core 2 whichextends along the centre and has thinner laterally projecting portionson each side which form friction wings 4. Ribs 5 project at intervalsfrom the wings.

FIGS. 5 and 6 illustrate the fifth and sixth embodiments of theinvention respectively, which are similar to the fourth embodiment,except for the method in which the frictional engagement with the earthis increased. The embodiment of FIG. 5, rather than having ribsprojecting from its friction wings 4, instead has perforations 57 forassisting frictional interaction with the earth. The perforations 57 areformed by cutting slots at intervals along the friction wings andopening the slots. Thus, the lateral edges of the wings have projections58 and recesses 59 caused by this action. These further assist inengagement with the earth. In FIG. 6 the friction wings 4 havecorrugations 60; in other words they are rippled up and down with arespect to the core 2.

A seventh embodiment 610 is shown in FIG. 12. This strip has an outercovering 611 of perforated PVC which surrounds a plastics watertransmitting portion 612 and two cores 615. The outer covering 611 isprovided with small perforations (not shown) to allow the ingress ofwater as will be explained below. It is further provided with mouldedribs 612A to improve the engagement of the strip with backfill material619.

The water transmitting portion 612 is a wafer like member of plasticsmaterial which has channels 613 along its length in order to allow waterto be transmitted along the strip. Communicating with the channels areopenings 614 to enable water to flow into the channels. Thus, in use,water in the backfill material, which will be under pressure, will beforced through the perforations in the outer covering into the openings614 and will then be able to flow along channels 613 towards the ends ofthe strip.

The cores 615 provide the strip of the present embodiment with thenecessary tensile strength to enable it to transmit forces along itslength. Each core 615 comprises a sheath 616 which holds a bundle offilaments 618 which may be wires or polymer fibres. The latter arepreferably used because they will not be corroded if water penetratesthe sheath 616.

FIG. 13 illustrates a way of providing a connection to the stabilisingstrip 610 of FIG. 12. This is achieved by allowing parts of the cores615 to project from one end of the strip where they are connectedtogether to form a loop 617. This loop may be connected around asuitable device 620 attached to a facing element 622. As an alternativeto connecting the two cores together, a continual core may be used whichforms both cores 615 and the loop 617 without the need for a joint.

FIG. 7 illustrates an apparatus 100 which is particularly suitable forproducing strips of the first embodiment. A coil of reinforcing barsteel 102 is provided adjacent to a reinforcing bar straightener 103.The steel is fed from the coil through the straightener and then to acutting machine 104 which is adjusted to cut the steel to lengths of bar101 corresponding to the length of strip 1 which is required. The barsare then passed into a hopper 105 from which they may be fed to theremaining part of the apparatus.

Next, each bar 101 is fed from the bottom of the hopper 105 into aplastics extrusion dye 106. Into this dye is fed the raw plasticsmaterial 107 from a bin 108 in which it has been mixed with appropriateadditives. The bin is heated and the molten plastic is fed by a screwpump 109 into the extrusion dye 106. The extrusion dye is provided withheater coils in order to maintain the plastics material in the moltenstate whilst it is moulded around the bar. The bar may be pushed orpulled through the dye and as it advances it is encased in the plasticsmaterial which forms the casing 3. After it leaves the dye 106 the bar,now coated with plastics, is hot rolled through a pair of rollers 110which produce the ribs 5 on the wings 4 of the coated strip 1. Ifdesired, the end of the strip may be sealed in order to protect the endsof the bar and then the plastics material is allowed to set thoroughly.

FIG. 8 illustrates an apparatus 200 which is generally similar to thatof FIG. 7, except that it is adapted for producing strips of the secondembodiment in which the tensile portion is a core of polymer yarns. Theillustrated apparatus provides a continuous process in which the core ispulled in the direction of arrow P through the apparatus. The extrusioncomponents are identical to those of FIG. 7. However, the reinforcingbar, coil straightener, cutting machine and hopper are replaced by anumber of coils 201 of yarn 202 and a device 203 in which the yarns arebrought together to form a single core 204. This core is then pulledthrough the extruding die 106 and rollers 110. The strip 1 once madecould be wound onto a drum and cut to desired lengths on site, or,alternatively, cutting apparatus could be added after the extrusionapparatus. Depending on the type of core material, on the type of soilin which the strip is to be placed, and on the service life required fora structure to be erected using the strips, their ends may or may not besealed when the strips are cut.

FIG. 9 illustrates an apparatus 300 for making strips of the firstembodiment in which the casing 3 is formed (for example by extruding androlling) in two separate parts 301,302 between which the core 2 issandwiched. The core is fed from a coil of reinforcing bar material 102through a reinforcing bar straightener 103 and then between coilscontaining the casing parts 301 and 302. One of these coils is locatedabove the bar and the other directly beneath it, and as the core 2 isfed between them the material unrolls from the coils thereby sandwichingthe core. A pair of press and weld cylinders 306 is provided downstreamof the coils to seal the plastics material in position around the core.In an alternative arrangement, the coils may be located on each side ofthe bar, with the cylinders 306 having their axes arranged vertically.The apparatus may be arranged such that the action of pulling the core 2will by itself unwind the parts 301,302 of the casing material from thecoils. Further apparatus may be provided downstream of the press andweld cylinders 306 in order to cut strips of the required length. Itwill be appreciated that similar apparatus could be useful producing thestrips of the second embodiment if yarn-handling apparatus of the typeillustrated in FIG. 8 were used in place of the reinforcing bar coil 102and reinforcing bar straightener 103.

FIGS. 10 and 11 illustrate apparatus for rolling strips of, for example,steel in order to provide strips of the fourth and fifth embodimentsrespectively. FIG. 10 illustrates an apparatus 400 in which a strip ofsteel 401 passes through a pair of rollers 402. The rollers have a waist403 which provides a raised, central portion 404 to the strip, therebyforming its core 2. On each side of the waist there are a series ofindentations 405 which provide ribs 5 on the friction wings 4. Thespacing of the rollers 402 determines the thickness of the wings.

In the apparatus 500 of FIG. 11 two pairs of rollers are provided. Thefirst pair 501 serve to form the core 2 of the strip 1 and are providedwith a waist portion 502 of an appropriate profile to achieve this. Therollers 501 are also spaced from each other by a distance whichdetermines the thickness of the friction wings 4. After passing throughthe first rollers, the strip passes through a second pair of rollers 503which as well as having a waist portion 504 to accommodate the core 2 ofthe strip are provided with pairs of cutters 505. It will be noted thatthese cutters are arranged to cut slits in the wings of the strip andalso to open up the slits in a lateral direction as the strip passesbetween the rollers 503. In this way a series of apertures 57 isprovided in the wings 4 and the lateral sides of the wings are providedwith a series of projections and recesses.

If desired, the cutting pair of rollers 503 may be providedindependently of the rollers 501, for example in another plant. In fact,such cutting rollers may be used directly on a conventional steel strip,i.e. one without a thickened core. In this case, the tensile portion ofthe strip comprises an uninterrupted longitudinal region, whilst thelateral portion for frictional engagement with the earth comprises aregion of the same thickness but formed with apertures. The provision ofthe apertures increases the overall width of the strip for the amount ofmaterial used.

While preferred embodiments and methods have been set forth, theinvention is to be limited only by the following claims and equivalentsthereto.

We claim:
 1. An elongate stabilizing strip for use in stabilized earthstructures, comprising, in combination:a longitudinal, tensile resistivecore, and lateral projections extending laterally outwardly fromopposite sides of the core for frictional engagement with earth saidcore and projections together defining the strip for stabilized earthstructures.
 2. The strip of claim 1, wherein the strip has oppositeedges and the lateral projections extend to the edges and wherein thecore has a thickness greater than the thickness of the lateralprojections.
 3. The strip of claim 1 wherein the lateral projectionsalso extend in the longitudinal direction of the core.
 4. The strip ofclaim 1 including a plurality of generally parallel longitudinal,tensile resistive cores, said cores connected together by horizontal,lateral projections.
 5. The strip of claim 1 wherein the lateralprojections include means for enhancing frictional interaction with theearth.
 6. The strip of claim 1 wherein the lateral projections includefriction enhancing means taken from the group consisting of ribs,corrugations, perforations and combinations thereof.
 7. The strip ofclaim 1 further including an integral fastening member at one end forengagement with means for fastening the strip in a stabilized earthstructure.
 8. The strip of claim 1 wherein the core and projections aremade from the same material.
 9. The strip of claim 1 wherein the coreand projections are unitary.
 10. The strip of claim 1 wherein the coreis made from a material having a greater tensile strength than thematerial of the projections.
 11. The strip of claim 1 wherein the coreis made from a steel material and the projections are made from aplastic material.
 12. The strip of claim 1 wherein the core is made frompolymer yarn or drawn bulk polymer and the projections are made from aplastic material.
 13. The strip of claim 1 wherein the core is enclosedwithin the material forming the projections.
 14. The strip of claim 1including means for collection and transport of water longitudinallythrough the strip.
 15. The strip of claim 1, in combination withparticulate material, to form a stabilized earthen structure.
 16. Amethod of manufacture of a reinforcing strip for use in stabilizedearthen structure to frictionally engage earth, said strip having alongitudinal, tensile resistive core and horizontal, lateral projectionsextending laterally outwardly from opposite sides of the core,comprising the steps ofproviding a longitudinal core; and molding thelateral projections for frictional engagement with earth onto the core.17. The method of claim 16 wherein the molding step is comprised ofrolling a strip of material to form the lateral projections.
 18. Themethod of claim 17 including the further step of forming apertures inthe lateral projections.
 19. The method of claim 16 including the stepof providing a core of higher tensile strength material than tensilestrength of the material of the lateral projections, and subsequentlymolding the lateral projections to surround the core.
 20. The method ofclaim 16 wherein the molding step comprises forming the lateralprojections by extrusion.
 21. The method of claim 16 wherein the moldingstep comprises the step of forming first and second parts of the lateralprojections and forming the core therebetween.
 22. An elongatestabilizing strip for use in stabilized earth structures of the typeincluding a facing wall, said strip comprising, in combination:anelongate tensile portion having a wall attachment end and an oppositeend; means for attaching the wall attachment end to a wall; and lateralportions comprised of a material different than the tensile portion,said lateral portions attached to and extending laterally outwardly fromthe elongate tensile portion, said lateral portions positioned forfrictional engagement with earth.
 23. An elongate stabilizing strip foruse in stabilized earth structure of the type including compacted earthhaving a plurality of strips positioned therein, said strip comprising,in combination:an elongate tensile member comprised of a flexible coreof a first material extending longitudinally; and horizontal, lateralprojections of a second material attached to an extending laterallyoutwardly from the core for frictional engagement with compacted soil.24. An elongate stabilizing strip for use in stabilized earth structuresof the type including compacted earth having a plurality of stripspositioned therein, said strip comprising, in combination:an elongatetensile member comprised of a flexible core extending longitudinally;and horizontal, lateral projections separate from and attached to thetensile member, said projections extending laterally outwardly from thecore and positioned for frictional engagement with compacted soil. 25.The strip of claims 1, 22, 23 or 24 in combination with compactedparticulate material.
 26. An elongate stabilizing strip for use instabilized earth structures comprising, in combination:a longitudinal,tensile resistive core; lateral projections extending from oppositesides of the core for frictional engagement with earth; and means forcollection and transport of water longitudinally through the strip. 27.A method of manufacture of a reinforcing strip for use in stabilizedearthen structure to frictionally engage earth, said strip having alongitudinal, tensile resistive core and lateral projections fromopposite sides of the core, comprising the steps of:providing alongitudinal core; molding the lateral projections for frictionalengagement with earth onto the core; and forming apertures in thelateral projection.
 28. An elongate stabilizing strip for use instabilized earth structures comprising, in combination:a longitudinal,tensile resistive core; lateral projections extending from oppositesides of the core for frictional engagement with earth; and apertures inthe lateral projections.
 29. An elongate stabilizing strip for use instabilized earth structures of the type including facing panels, saidstrip comprising, in combination:a longitudinal, tensile resistive corestructure; and lateral projections extending laterally outwardly fromopposite sides of the core structure, said core structure forming a loopat one end for connection to a stabilized earth structure panel, saidloop being generally in the same plane as the lateral projections. 30.An elongate stabilizing strip for use in stabilized earth structures ofthe type including facing panels, said strip comprising, incombination:lateral projections of a second material attached to thecore and extending laterally outwardly from at least one side of thecore for frictional engagement with earth; and a connector attached tothe core for attaching the strip to a panel.
 31. An elongate stabilizingstrip for use in stabilized earth structures of the type includingfacing panels, said strip comprising, in combination:a longitudinaltensile resistive core; lateral projections adhered to the core andextending laterally outwardly from the core for frictional engagementwith earth, said lateral projections generally coplanar; and a connectorfor attaching the strip to facing panels, said connector attached at oneend to the core and comprising a connection passage coplanar with thelateral projections.
 32. An elongate stabilizing strip for use instabilized earth structures comprising, in combination:a longitudinalcore; and lateral projections attached to the core and extending inopposite directions from opposite sides of the core to define agenerally planar strip, said lateral projections including an outsideedge section having a thickness greater than at least a portion of thethickness of the projections intermediate the core and the outside edgesection.
 33. An elongate stabilizing strip for use in stabilized earthstructures comprising, in combination:a longitudinal core; and lateralprojections attached to the core and extending laterally from the coreto define a wing, said wing including perforations therethrough forengagement of the wing with the earth.
 34. An elongate stabilizing stripfor use in stabilized earth structures comprising, in combination:alongitudinal, tensile core; and lateral projections attached to the coreand extending laterally from the core, said projections and coredefining a generally planar strip, said projections further includingoutwardly extending ribs on the surface of the projections.
 35. Anelongate stabilizing strip for use in stabilized earth structurescomprising, in combination:a longitudinal tensile core; and lateralprojections attached to the core and extending laterally from the coreto define a generally planar strip, said projections includingstructural means for assisting frictional engagement of the projectionswith earth said structural means taken from the group consisting ofopenings, ribs, corrugations, indentations, slots, recesses, andcombinations thereof.